DE102010031622A1 - Kraftstofffördereinrichung - Google Patents

Abstract

A fuel delivery device for a fuel injection device of an internal combustion engine with a delivery pump (10) and with at least one high-pressure pump (16) is proposed. The feed pump (10) feeds fuel from a storage container (12) to the suction side of the high pressure pump (16) and the high pressure pump (16) feeds fuel in a high pressure area (18). The feed pump (10) has an adjustable displacement volume, which means that a variable amount of fuel can be fed at the same speed.

Description

The invention relates to a fuel delivery device for a fuel injection of an internal combustion engine according to the preamble of the independent claim.

State of the art

Such a fuel delivery device and its operation is already by the Series Diesel common rail injection system (ISBN-978-3-86522-010-3) of the Robert Bosch GmbH or EP 1 195 514 A2 known. This fuel delivery device has an electrically driven delivery pump through which fuel is conveyed to the suction side of a high-pressure pump. The high-pressure pump delivers fuel into a high-pressure region, from which at least indirectly at least one injector of the fuel injection device is supplied with fuel. An electrical control device is provided which receives a signal for the pressure prevailing in the high-pressure region via a sensor device. By the electrical control device, the electric drive of the feed pump is variably controlled, so that the fuel delivery amount of the feed pump can be changed by varying the speed. As a result, adapted to the operating conditions fuel delivery of the feed pump is possible, however, has a high drive power demand and electrical control and sensor devices needed.

Disclosure of the invention

The fuel delivery device according to the invention with the characterizing features of claim 1 has the advantage that the feed pump has an adjustable displacement volume, whereby a variable amount of fuel at the same speed can be promoted. The ability to vary the fuel delivery at the same speed, the regulation of the fuel flow rate via the electric drive and the control and sensor devices can be omitted, which costs can be saved. The feed pump can be driven either mechanically or electrically and vary their fuel delivery at the same speed.

With the measures of the dependent claims advantageous refinements and improvements of the invention are possible.

In a first advantageous embodiment of the fuel delivery device, the delivery pump delivers a variable amount of fuel that varies between a zero delivery amount and a maximum amount. The maximum amount is determined by the maximum displacement of the feed pump. Due to the wide range in which the fuel delivery rate can vary, an optimal adjustment of the fuel delivery to the fuel demand in the high pressure range is possible. It eliminates additional components such. As the electric drive of the feed pump, an electrical control device for controlling the electric drive or a metering unit (ZME), which adapts the fuel delivery to the needs of the high-pressure pump.

In an advantageous development of the method, the adjustable displacement volume is regulated via a control pressure. There are no additional external control devices are required to adjust the fuel delivery of the feed pump to the needs in the high pressure area. Furthermore, there is no need for sensor units for pressure detection, since the pressure does not have to be determined, but directly affects the flow rate. This reduces the cost and simplifies the construction of the low pressure circuit.

In a further advantageous development, the control pressure is the fuel pressure on the pressure side of the feed pump. In this case, the delivery pump adapts optimally to the fuel demand in the high-pressure range. There are no other components, such as overflow valve and metering unit can be used. Since the amount of fuel required by the high-pressure pump is always conveyed by the delivery pump and too much subsidized fuel does not have to be diverted, the fuel consumption is reduced.

A particular advantage is obtained when the control pressure is the fuel pressure between a fuel filter installed on the pressure side and the suction side of the high-pressure pump. The feed pump adjusts the pressure on the suction side of the high-pressure pump, regardless of the pressure loss of the fuel filter. Influencing factors such as the load condition of the fuel filter or temperature-related volatilization of the fuel filter are compensated.

Another advantage arises when the control pressure is the fuel pressure in the return to the reservoir. Also in this solution, the use of other components, since it can be dispensed with the metering unit. It serves too much subsidized fuel as a control pressure, so that a different interpretation of the actuators of the feed pump is possible. Depending on the design of the fuel in the return to the reservoir is controlled by an overflow valve on the suction side of the high pressure pump or the fuel in the return to the reservoir is controlled by a pressure control valve in the high pressure area.

A particular advantage arises when the control pressure is the fuel pressure in the high-pressure accumulator. This results in a control loop that regulates the pressure in the high-pressure accumulator without electrical actual value detection, electrical signal processing and electrical actuators. Furthermore, the elimination of the pressure control valve on the high-pressure accumulator is possible.

Another advantage arises when the adjustable displacement volume is regulated via a control pressure. The control pressure is changed via an electrical control device and a pressure control valve. This opens up the possibility to change the delivery characteristics and thus to control the fuel delivery of the pump controlled. Depending on the engine operating point or depending on the pressure in the high-pressure accumulator, the setting of the control pressure for changing the displacement volume can be changed.

Advantageously, the use of a vane pump or an external gear pump or a roller-cell pump or an internal gear pump or a pendulum slide pump as a pump with adjustable displacement, as can be used on known pump types and reduces the development effort.

embodiments

Preferred embodiments of the invention are illustrated in the drawing and explained in more detail in the following description.

Show it:

1 a fuel delivery device in a schematic representation according to a first embodiment of the invention;

2 a pump with adjustable displacement volume in a schematic sectional view of a fuel delivery device;

3 a fuel delivery device in a schematic representation according to a second embodiment of the invention;

4 a fuel delivery device in a schematic representation according to a third embodiment of the invention;

5 a fuel delivery device in a schematic representation according to a fourth embodiment of the invention.

1 shows a fuel delivery device in a schematic representation according to a first embodiment of the invention. The fuel delivery device has a delivery pump 10 on, the fuel from a reservoir 12 sucks. Through the feed pump 10 Fuel is to the suction side of at least one high-pressure pump 16 promoted, which is also part of the fuel conveyor. The drive of the feed pump 10 can be done mechanically via clutch, gear or timing belt by the motor or the high pressure pump. Alternatively, the feed pump 10 have an electric drive that can be operated with variable power and thus variable speed or constant power and speed.

By the at least one high-pressure pump 16 Fuel is in a high pressure area 18 promoted the fuel delivery device, for example, a high-pressure accumulator 18 includes. From the high pressure area 18 be one or more injectors 20 fueled, each cylinder of the internal combustion engine being an injector 20 assigned.

The pump 10 can at the high pressure pump 16 arranged to be integrated in this or removed from the high-pressure pump 16 be arranged, for example in the reservoir 12 or in a hydraulic line between the reservoir 12 and the high pressure pump 16 , The high pressure pump 16 has at least one pump element, which in turn has a pump piston which is driven in a lifting movement. The high pressure pump 16 may have its own drive shaft through which the stroke of the pump piston is effected via a cam or eccentric. The drive shaft of the high-pressure pump 16 is mechanically driven, for example via a transmission or a belt drive of the internal combustion engine, so that the speed of the high-pressure pump 16 is proportional to the speed of the internal combustion engine. Alternatively, it can also be provided that the high-pressure pump 16 has no own drive shaft and the lifting movement of the pump piston is effected by an eccentric cam or a shaft of the internal combustion engine. It can also be several high-pressure pumps 16 be provided. Alternatively, a hydraulic actuation may be provided.

The pump 10 can be removed from the at least one high pressure pump 16 be arranged, for example, in the reservoir 12 , The pump 10 is via a hydraulic line 6 with the suction side of the at least one high-pressure pump 16 connected. In the hydraulic line can be a fuel filter 38 be arranged to prevent dirt particles in the high-pressure pump 16 and in the high pressure area 18 reach.

In the high pressure area 18 can be a pressure control valve 22 be provided by the in the high pressure area 18 prevailing pressure is controlled. Is in the high pressure area 18 too high a pressure exists, so can via the pressure control valve 22 excess fuel via the hydraulic line 2 in the return 8th to the reservoir 12 reach. Thus, in the high pressure area 18 a required pressure depending on operating parameters of the internal combustion engine can be adjusted.

Excess fuel from the drive area of the high-pressure pump 16 can via the hydraulic line 28 to the return 8th and thus to the reservoir 12 be directed. Will more fuel than needed by the feed pump 10 to the suction side of the high-pressure pump 16 promoted, so can excess fuel through a spill valve 34 at the high pressure pump 16 over the hydraulic line 28 to the return 8th and thus to the reservoir 12 be directed.

Furthermore, a fuel return of the injectors 20 over the hydraulic line 4 to the return 8th and thus to the reservoir 12 be directed.

In 2 is exemplified a pump with adjustable displacement volume in a schematic sectional view of a fuel delivery device. It has a housing 40 on, in which there is a rotor 42 with at least one or more wings 44 located. The rotor 42 rotates about an axis that goes perpendicular to the leaf through a center M1.

A circular stator ring 46 is from a first actuator piston 48 and a second actuator piston 50 clamped. The two adjusting pistons are arranged opposite each other. There may be another point of support of the stator ring 46 exist by a height adjustment screw, not shown. The axis of the circular stator ring 46 passes through a center M2. The back of the first actuator piston 48 is via a hydraulic line 26 subjected to a control pressure. The control pressure is provided by a Krafftstoffdruck within the fuel delivery device in the described embodiment. The second control piston 50 acts on the first actuator piston 48 contrary and is from a spring 52 held in a certain position. Due to the control pressure and the spring force, two forces act in opposite directions on the stator ring 46 ,

Inside the stator ring 46 rotates the electrically or mechanically driven rotor 42 and the blades guided in the rotor 44 are caused by centrifugal forces against the stator ring 46 pressed. The cells required to transport the fuel 54 be through the rotation of the rotor 42 getting bigger and filling up with fuel via a suction channel 56 the fuel from the reservoir 12 sucks. With reaching the largest cell volume, the cells 54 separated from the suction side and receive in a further rotation connection to the pressure side. Upon further rotation, the cells become 54 narrows and presses liquid over the pressure channel 58 in a hydraulic line leading to the suction side of the high-pressure pump 16 leads.

Depending on the force resulting from the fuel pressure on the first actuator piston 48 results and the force of the spring 52 on the second control piston 50 exercises, the stator is 46 moved in the housing. If both forces are equal, the stator ring is in the middle position and the two center points M1 and M2 lie on one another. In this case, the flow rate of the fuel goes back to a zero flow, ie the flow rate is zero.

The fuel pressure drops, leaving the force through the spring 52 greater than the force resulting from the fuel pressure on the first actuator piston 48 results, so shifts the spring 52 the stator ring 46 in an eccentric position in which the centers M1 and M2 are no longer on top of each other. Since the suction and the pressure side are separated from each other, displaces the feed pump 10 again fuel. With increasing distance of the centers M1 and M2, the displacement volume of the pump becomes larger.

The pump 10 can be operated at the same speed or variable speed via a mechanical or electric drive. The speed of the feed pump 10 influences the amount of fuel delivered. By regulating the control pressure, a variable amount of fuel can be delivered at the same speed.

An example of a feed pump 10 with adjustable delivery volume is the "adjustable vane pump, type PV7" from Bosch Rexroth, which in its construction of the described pump 10 but would have to be adapted to the dimensions and requirements of a fuel delivery system.

Alternatively, it can be used as a feed pump 10 with adjustable delivery volume also use an external gear pump or a roller cell pump or an internal gear pump or a pendulum vane pump. An example of a volume-adjustable pendulum slide pump is in the published patent application DE 101 02 531 A1 shown.

In the embodiment according to 1 the control pressure is the fuel pressure on the pressure side 6 the feed pump 10 , Via a hydraulic line 26 the control pressure acts on the first control piston 48 and thus influences the displacement volume of the feed pump 10 , If a pressure side fuel filter 38 is provided, alternatively, the pressure on the suction side of the high-pressure pump 16 between fuel filter 38 and high pressure pump 16 serve as control pressure.

If, due to a change in the operating conditions, more fuel is needed for a short time than required by the feed pump 10 to the high pressure pump 16 promoted, so it builds in the hydraulic line 6 an increased pressure. The pressure in the hydraulic line 6 increases depending on the amount of overfed fuel. Due to the increase in pressure, the control pressure on the first control piston increases 48 , the displacement volume of the feed pump 10 is reduced, thereby reducing the flow rate of the fuel. The fuel quantity of the feed pump 10 meets the needs of the high pressure pump 16 customized. When the fuel pressure in the hydraulic pipe 6 drops because of the high pressure pump 16 has an increased fuel requirement, also reduces the control pressure and the feed pump 10 increases the flow rate of the fuel. The fuel delivery of the feed pump 10 meets the needs of the high pressure pump 16 customized.

To simplify the low pressure circuit but with the same effect, a control of the feed pump 10 be made on the own delivery pressure.

3 shows a further embodiment of the invention. Here, the control pressure is the fuel pressure in a return 8th to the reservoir 12 , Through a throttle 24 builds up in the return 8th to the reservoir 12 a fuel pressure, via the hydraulic line 26 or directly with the first actuator piston 48 the feed pump 10 connected is. On the throttle 24 in the return 8th to the reservoir 12 can be omitted if a back pressure by a jet pump, not shown in the return 8th to the reservoir 12 arises.

If, due to a change in the operating conditions, more fuel is needed for a short time than required by the feed pump 10 to the high pressure pump 16 promoted, so is using an overflow valve 34 the excess fuel via the hydraulic line 28 to the return 8th deactivated. The pressure in the return 8th increases depending on the amount of overfed fuel. Due to the pressure increase in the return 8th the control pressure rises to the first actuating piston 48 , the displacement volume of the feed pump 10 is reduced, thereby reducing the flow rate of the fuel. Is little fuel from overflow valve 34 in the return 8th deactivated, so the control pressure and the delivery pump decreases 10 increases the flow rate of the fuel. The fuel delivery of the feed pump 10 is due to the fuel demand of the high pressure pump 16 customized.

Alternatively, the fuel in the return 8th to the reservoir 12 from the pressure control valve 22 in the high pressure area 18 be repulsed. The pressure control valve 22 can be directly at the high-pressure accumulator 18 or at the high pressure pump 16 or between high-pressure pump 16 and high pressure storage 18 are located. The pressure control valve 22 is regulated by an electrical control unit. Is there a higher pressure than required in the high pressure range 18 , so excess fuel with the help of the pressure control valve 22 deactivated. The pressure in the return 8th increases depending on the amount of fuel removed. The increased fuel return increases the pressure in the return line 8th in front of the throttle 24 and the control pressure on the first actuator piston 48 rises. The displacement volume of the feed pump 10 is reduced, thereby reducing the flow rate of the fuel. Is getting little fuel from pressure control valve 22 in the return 8th deactivated, so the control pressure and the delivery pump decreases 10 increases the flow rate of the fuel.

4 shows a further embodiment of the invention. Here, the control pressure of the fuel pressure in the high-pressure accumulator 18 , Through the hydraulic line 26 the pressure acts in the high pressure area 18 directly on the first control piston 48 the feed pump 10 and thus influences the displacement volume of the feed pump 10 , Dominates in high pressure storage 18 too high a pressure, the fuel delivery of the feed pump 10 reduced, the pressure in the high-pressure accumulator 18 too low, the fuel delivery of the feed pump 10 increased, otherwise it remains constant.

In all the embodiments of the invention shown, the rear side of the second actuating piston can be used for the controlled influencing of the displacement volume 50 be subjected to a control pressure. This acts on a force resulting from the force of the spring 52 and the control pressure, on the second actuator piston 50 , The control pressure acting on the second control piston 50 acts, comes from any point of the fuel delivery device and should be lower than the control pressure on the back of the first actuator piston 48 acts.

5 shows a further embodiment of the invention. Here, the control pressure of the fuel pressure on the pressure side of the feed pump 10 , The control pressure is via a pressure control valve 15 , which with an electronic control device 19 connected, controlled. The electrical control device 19 is with a pressure sensor 17 in the high pressure area 18 connected, which information about the pressure in the high pressure area 18 to the electronic control device 19 supplies. Depending on the pressure in the high pressure area 18 controls the electrical control device 19 the pressure control valve 15 and thus influenced via the control pressure controlled the delivery rate of the feed pump 10 , Unnecessary fuel is fed via a hydraulic line into the reservoir 12 deactivated. Through the pressure control valve 15 is a stepless adjustment of the force on the second control piston 50 the feed pump 10 possible. By changing the control pressure, the delivery characteristics of the feed pump changed 10 and there are different displacement volumes of the feed pump 10 at the same control pressure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1195514 A2 [0002]
• DE 10102531 A1 [0034]

Cited non-patent literature

• Series Diesel common rail injection system (ISBN-978-3-86522-010-3) of Robert Bosch GmbH [0002]

Claims (13)

Fuel delivery device for a fuel injection device of an internal combustion engine with a delivery pump ( 10 ) and with at least one high-pressure pump ( 16 ), whereby by the feed pump ( 10 ) Fuel from a reservoir ( 12 ) to the suction side of the high pressure pump ( 16 ) and by the high pressure pump ( 16 ) Fuel to a high pressure area ( 18 ), characterized in that the feed pump ( 10 ) has an adjustable displacement volume, whereby a variable amount of fuel at the same speed can be promoted. Fuel delivery device according to claim 1, characterized in that the feed pump ( 10 ) conveys a variable amount of fuel that varies between a zero delivery amount and a maximum amount, the maximum amount being determined by the maximum displacement of the delivery pump ( 10 ) given is. Krafftstofffördereinrichtung according to claim 1 or 2, characterized in that the adjustable displacement volume is regulated by a control pressure. Fuel delivery device according to claim 3, characterized in that the control pressure of the fuel pressure on the pressure side ( 6 ) of the feed pump ( 10 ). Fuel delivery device according to claim 3, characterized in that the control pressure of the fuel pressure between the fuel filter ( 38 ) and the suction side of the high pressure pump ( 16 ). Fuel delivery device according to claim 3, characterized in that the control pressure of the fuel pressure in a return ( 8th ) to the reservoir ( 12 ). Fuel delivery device according to claim 3, characterized in that the control pressure of the fuel pressure in the high-pressure accumulator ( 18 ). Fuel delivery device according to claim 6, characterized in that the fuel in the return ( 8th ) to the reservoir ( 12 ) from an overflow valve ( 34 ) on the suction side of the high-pressure pump ( 16 ) is discarded. Fuel delivery device according to claim 6, characterized in that fuel in the return ( 8th ) to the reservoir ( 12 ) from a pressure regulating valve ( 22 ) in the high pressure area ( 18 ) is discarded. Fuel delivery device according to claim 3, characterized in that the adjustable displacement volume is additionally influenced by a control pressure. Fuel delivery device according to claim 10, characterized in that the control pressure via a pressure regulating valve ( 15 ) is set. Fuel delivery device according to claim 10 or 11, characterized in that the control pressure depends on an engine operating point and / or dependent on the pressure in the high-pressure accumulator ( 18 ) is set. Fuel delivery device according to claim 1, characterized in that the feed pump ( 10 ) is an adjustable vane pump, an adjustable external gear pump, an adjustable roller cell pump, an adjustable internal gear pump or an adjustable pendulum slide pump.

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